Flat lesions represent a significant challenge in gastroenterology. Removing of sessile and flat polyps, which may be associated with high risk for malignancy, requires, in most cases, usage of different techniques than those used for removing common polyps. These techniques may lead to the referral of patients to surgery instead of removal by the gastroenterologist. Other challenging lesions are nonpolypoid colorectal neoplasms (NP-CRNs). Barrett's esophagus is another common chronic condition. The prevalence in the U.S. population is estimated to be in the range of 1-2% of the adult population. Barrett's esophagus condition may lead to violent esophageal cancer, which is said to result in over 12,000 deaths per year in the U.S. alone and around 100,000 in China.
Management of Barrette's Esophagus.
Barrett's Esophagus (BE) is a common disorder that is a major risk factor for esophagus cancer. The prevalence of the disorder is estimated to be in the range of 1-2%. See Ronkainen J, Aro P, Storskrubb T, et al. (December 2005) “Prevalence of Barrett's esophagus in the general population: an endoscopic study”, Gastroenterology 129 (6): 1825-31. The range of severity can vary from early stage to different grades of dysplasia to cancer. Prior attempts to manage this condition with Argon coagulation yielded controversial results. Alternative methods are based on RF ablation (RFA) (Halo® System), photodynamic therapy (PDT), cryo, thermal therapy or surgery as endoscopic mucosal resection (EMR). No method resulted in wide clinical acceptance that can enable routine use in a broad population instead of “waiting and watching” in early stages in the disease and specific therapies including esophagus resection in more sever conditions.
Furthermore, as no single technique has been established as the preferred method, a combination of techniques is used in certain cases. For example, there may be a consensus that RFA is useful for patients with BE and high-grade dysplasia (HGD), BE and intramucosal carcinoma as an adjunct to endoscopic mucosal resection (EMR). The use of RFA for BE with low-grade dysplasia (LGD) or intestinal metaplasia is not clearly established, see David E. Fleischer_Virender K. Sharma, Interventional and Therapeutic Gastrointestinal Endoscopy. Front Gastrointest Res. Basel, Karger, 2010, vol 27, pp 140-146. On the other hand, EMR sometimes does not allow removing all of the Barrett's lining but can be successful in removing a small cancer or a localized area of high-grade dysplasia. Because it does not remove all of the Barrett's lining, the Barrett's lining left behind can develop other areas of high-grade dysplasia or cancer. Therefore, EMR is sometimes combined with photodynamic therapy in an attempt to remove remaining Barrett's tissue or with RF ablation. Conversely, several photodynamic therapy studies have also reported that a few patients have a situation in which the Barrett's lining does not completely go away but is still there, underneath the new normal-appearing squamous lining (and detected when biopsy is performed that shows that small areas of Barrett's lining are still there underneath the new squamous lining.) In such a case, another course of treatment with another technique might be beneficial.
Complications of the current available techniques include perforations (making a hole in the esophagus), bleeding, strictures, light sensitivity in PDT and even death.
Removal of Challenging Lesions in Intestine and Stomach.
Some of the polyps and adenomas (benign tumors) detected with an increasing percent in colonoscopy, with different imaging techniques, do not have a conventional “pedunculated” shape. Polyps that are not attached to the surface by a narrow elongated stalk are called sessile. Other polyps are not significantly elevated from the adjacent mucosa are called flat. Accordingly, the removal of large sessile and flat colorectal is more difficult than removal of pedunculated polyps and in many cases require using special endoscopy techniques to avoid perforation.
These lesions may be associated with high clinical risk. The incidence of cancer with submucosal invasion appears to be higher in flat-type lateral spreading tumors.
Endoscopic Mucosal Resection (EMR) is becoming the standard technique for resection of large sessile and flat colorectal lesions. For the more challenging lesions, Endoscopic Submucosal Dissection (ESD) can be used. ESD can be performed using a viscous injection solution for sustained submucosal lifting, a diathermy knife, and a plastic hood to help retract the polyp as it is dissected away from the muscularis propria.
Although these techniques are feasible anywhere in the colon, currently these techniques are technically challenging and time consuming and ESD carries a relatively high rate of major complication. Laser ablation is usually not perceived as an adequate solution for this application, as there is a need to assure adequate (i.e. complete) removal of pathological tissue and preferably to collect resected samples for histological analysis
There is thus an unmet need in the art for devices, systems and methods that would allow efficient and effective vascular interventions as well as removal of challenging lesions in the gastroenterology (GI) track (mainly in colon and stomach) and Barrett's esophagus management.
Removal of Challenging Lesions in Gynecology and Urology.
There is a need for effective and safe tools for removal of pathological tissue in gynecology (cervical uterus) and urology (urinary bladder, prostate), wherein the depth of resection can be controlled while risk of perforation and bleeding is minimized.
Peripheral and arterial vascular diseases are also a common problem which may directly lead to morbidity and death. In the U.S. alone it is estimated that over 4 million people suffer from peripheral artery disease which, in severe cases, is treated with surgery or even amputation.
Laser and Mechanical Based Solutions for Angioplasty, Atherectomy and Thrombectomy:
The current state of the art in laser ablation technology for vascular intervention is based on use of an Excimer lasers with dedicated catheters such as Spectranetics' CVX-300® laser and TURBO-Booster® catheter. These technologies are described, for example, in U.S. Pat. Nos. 6,673,064, 7,811,281 and 7,572,254. Due to technical and safety considerations, the excimer laser used, generally, is often a Xenon Chloride laser operative at 308 nm with pulse widths in the range of 100 nanoseconds. These technologies are not ideal and have some limitations. For example, when dealing with heavy calcified plaques, there is a risk of perforation and damage from debris/plaque fragments. Therefore, the procedure requires a complex, large and costly system and the length of the procedure is quite significant in a manner that seems to limit its wide clinical utility. In addition, the technique had difficulties in treatment of large vessels such as SFA (Superficial Femoral Artery) which is very important in management of peripheral artery disease (PAD) wherein vessels larger than 4-5 mm in diameter and long lesions have to be treated.
One of the reasons for the length of the process is that even one of the most advanced solutions, combining the TURBO-Booster® and the TURBO Laser Elite catheters, may require a number of steps starting with atherectomy to create an initial pilot channel through the whole lesion, for example using the laser catheter alone, and only at later stages the laser catheter is loaded into the introducer sheath. The use of the catheter is based on several passages, each after rotation of the catheter. See Schwarzwälder U, Zeller T, Tech Vasc Interv Radiol. 2010 March; 13(1):43-53.
Additional limitations of this solution include ineffective removal of arterial debris and high risk of artery walls injury, as mentioned, for example, in U.S. Pat. No. 6,962,585:                “An Excimer Laser Coronary Angioplasty system and procedure offered by Spectranetics of Colorado Springs, Colo., involves the insertion into an artery of a laser catheter containing a bundle of optical fibers and a stent with a guide wire. The laser catheter is advanced in the artery until the guide wire crosses a blockage, at which time bursts of ultraviolet (cool) laser light is transmitted through the fiber optic fibers to open a hole in the blockage. Thereafter, an x-ray contrast dye is injected into the blood stream to determine the extent to which the artery has been opened. This procedure does not remove substantial amounts of blockage because ultra violet radiation is too cool to melt the blockage. Rather, a hole is blasted through the blockage to accommodate the admission of a stent. While the catherization system includes a filter, the filter is not sufficient to catch all debris which may flow downstream.        Such prior systems have failed because they have not effectively removed arterial blockage from the artery walls, and have not effectively removed arterial debris from the artery once the arterial blockage has been dislodged. In addition, such prior systems have not adequately protected the artery walls from physical or thermal injury. Further, many of the prior art devices embody numerous parts which tend to fail or shatter in a high temperature/high vacuum environment.” (id, p. 1, In. 19)        
An alternative approach using IR laser for thermal heating of a tip used to cut the plaques to be removed with suction is disclosed in U.S. Pat. No. 6,962,585. This approach may suffer from the limitations and risk involved with plaque removal based on non-selective heating. The approach proposed in this case is to use arterial guards in the outer part of the catheter that may limit the passage of the catheter and avoid getting closer to the walls. Other attempts to use thermal effects include a hybrid thermal probe, wherein most of the laser energy (Argon or Nd:YAG) is used to heat the hot tip in the catheter, and part of it escapes as laser light. Clinical results were not satisfactory to enable routine clinical use.
Additional prior approaches include use of a laser to core the plaque and use of mechanical means to “ingest” and remove the plaque. See, for example, U.S. Pat. No. 4,979,939. In Canadian Patent No. 1,326,800 a fiber is introduced to create an opening through which the distal rotary is introduced and the second fiber is used to vaporize the material collected by the blade. U.S. Patent Application Publication No. 2010/0125253 discloses a dual tip catheter for treating chronic total occlusions through which a fiber may be introduced.
In view of the complexity and limitations of the laser based technologies, the systems based on excimer laser have had limited spread in clinical use, and alternative mechanical methods for atherectomy have been developed, for example, wherein the plaques are “shaved” (the EV3 product), “drilled” (the Pathway product) or “sanded” with a rotating diamond coated brush (the CSI product). Each of these techniques may often suffer from inherent limitations such as procedure length, injury to the blood vessels, difficulty in dealing with calcified plaques in certain cases and, on the contrary, dealing with soft plaque (see Schwarzwälder U, Zeller T, Tech Vasc Interv Radiol. 2010 March; 13(1):43-53) or discarding of plaque material into the blood stream.
It should be noted that it is assumed by experts in the area that injury of healthy tissue and the characteristics of the tissue after plaque is removed may affect the healing (and initial hyperplasia) and the rate of restenosis which seems to be a limitation of some of the above-mentioned techniques. Furthermore, in view of the limited capabilities to remove plaque with many prior techniques, their current utility is limited mainly for use in conjunction with low pressure balloon angioplasty used after plaque is partially removed. The balloon then opens the vessel with the remaining plaque material.
The need to deal with complete or partial blockage in vessels applies also to artificial grafts, such as those implanted in the legs for bypass, for hemodialyisis access and more.
In-Stent—Restenosis.
It is known in the art that in a significant percentage of the patients that underwent stent implantation, restenosis occurs within a few years after implantation. This is a major issue with bare-metal stents (BMS) and even introduction of drug eluting stents (DES) that show a robust decrease of restenosis still does not completely solve the problem.
Acute Blockage of Vessels.
There is also a need for tools that quickly open blood vessels in patients that suffer from ischemic stroke (caused by blockage of a blood vessel) or in heart attacks with the minimal risk of perforation.
Removal of Pacemaker and Defibrillator Leads.
Presently there is a growing need to remove pacemaker and defibrillators leads in a subset of patients due to several reasons such lead fracture, abrasion of the insulation causing shorting and infections. Approximately 5 million leads are implanted worldwide and it is estimated that 4-7% will have to be removed at certain time point. It is estimated that over 100,000 leads were extracted in the US and Europe in 2010.
There are several approaches to remove transvenously introduced ICD leads. If leads have been in place for only a short period, they can frequently be removed by simple traction. After the leads are in place for long time scar tissue may withholds the leads during traction, the force applied to the leads is limited by the tensile strength of the insulation and conductor coils, therefore locking stylets and sheaths are used to enable a more forceful tension, but successful lead removal can still be very problematic when the leads is attached to sensitive tissue such myocardial wall. In severe cases lead extraction may require open surgery. The Spectranetics Excimer Laser and Cook Medical's Evolution products are currently used for lead removal using transcatheter techniques. The “debulking” of the lead using an excimer laser has yielded good clinical results but requires a large and expensive laser that does not allow wide use in any cardiology unit and a relative long learning curve is required.
There is a need for an effective and safe solution for removal of pace makers and defibrillator leads in patients.